My Cloud accessible, but I am unable to add new sync folder

Using WD sync 1.3.5949 on Windows 10
I have 5 folders which all sync correctly.
I can access all folders on my WD Cloud device via network and via app. New files are synced immediately.
I can see all files via myCloud.com.
But: when I try to sync from a new local folder, I can select the local folder and when I then I try to “select a folder on your device to sync to”, I get an error message: “Not able to connect to remote server”

Hello,

I have seen more than that working at the same time. So, it’s not a limitation issue.

Have you tried resetting the unit and testing that again?

I have tried resetting - twice. No change.
I can without problems use WD smartapp to backup - also add and delete back-up settings.
That works fine.
My conclusion is that there must be error in the app WD sync - latest version.
OR???